Each state has individual divorce laws, which means that what’s true in one place is not necessarily true in another. Interpretation varies a lot from state to state when it comes to wills following divorce. This is why both spouses need to be informed and aware of relevant issues. It’s a good idea to set up a meeting with your estate planning attorney early on in the divorce process, if not immediately after you have the relevant paperwork. 
If a will is private, or if a death happens before the individual has had time to update it post-divorce, there is no guarantee of intent that will be honored. That’s why it’s valuable to re-draft a second will, outlining a revocation clause for the previous will at all. This reduces confusion and opportunities for argument.
If there is a trust involved, it depends on whether the trust was created as revocable or irrevocable. An irrevocable trust can be updated, but a revocable one may require that divorce papers declare the ability to amend or dissolve it. Consult with your estate planning specialist for more information.